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Vol. 39 No. 3, 2000
Participation
of Glycoproteins on Zooxanthellal Cell Walls in the Establishment of a
Symbiotic Relationship with the Sea Anemone, Aiptasia pulchella
Ku-Lin Lin1, Jih-Terng Wang1, and Lee-Shing Fang1,2,*
1Institute of Marine Resources, National Sun Yat-sen University, Kaohsiung, Taiwan 804
2National Museum of Marine Biology and Aquarium, Che-Cheng, Pingdong, Taiwan 944
Ku-Lin Lin, Jih-Terng Wang, and Lee-Shing Fang (2000) Recent
studies have revealed that glycoproteins on cell membranes are usually
in- volved in the process of cell recognition. This study provides
evidence to demonstrate the role of cell surface glycoproteins of
zooxanthellae in establishing a symbiotic relationship between algae
and a sea anemone host. When freshly isolated zooxanthellae from the
sea anemone, Aiptasia pulchella,
were incubated with trypsin, α-amylase, N-glycosidase F, or
0-glycosidase, the algae could not infect bleached animals as
efficiently as did the control algae. If the glycoproteins on the
surface of the zooxanthellae were masked with lectins, the infection
rate also declined significantly. Further, the glycoproteins on the
cell walls of zooxanthellae were isolated and char- acterized with
SDS-polyacrylamide gel electrophoresis and Western blotting. There are
10 protein bands in total revealed by Coomassie blue and silver
staining, of which 5 are identified as glycoproteins. Two types of
terminal sugar residues, mannose-mannose and
galactose-β(1-4)-N-acetylglucosamine, were characterized among them.
The most abundant glycoprotein with a molecular weight of 64 kDa
carries a terminal sugar mannose. These data indicate that the
glycoproteins on cell walls of zooxanthellae are a crucial factor in
the successful establishment of the symbiotic relationship between
zooxanthellae and A. pulchella.
Key words: Symbiodinium, Cnidarians, Endosymbiosis, Lectin, Recognition.
*Correspondence: Tel: 886-7-5255027. Fax: 886-7-5255027. E-mail: lsfang@mail. nsysu.edu.tw
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